One known apparatus for detecting every person inside a room processes images picked up by a camera such as a visible light camera or infrared camera. Another known apparatus used for the same purpose employs active sensors such as infrared sensors or ultrasonic sensors to detect a person within a narrow region. A further known apparatus makes use of a passive sensor equipped with a shutter mechanism.
In the prior art apparatus for detecting the presence of a person or persons with a camera, it is necessary to correct the processed image, depending on the condition of the camera. Also, it is not easy for the user to set up the apparatus. Furthermore, the apparatus is bulky. In addition, it consumes a large amount of electric power. Further, the optical system must be so set up that the dead angle is compensated for. Therefore, it is inevitable that the optical system is separate from the image processing portion. Moreover, the camera puts stress on the subject person. Hence, contrivance is needed in the field of house automation, especially in the way in which the optical system is received in the apparatus.
The person presence-detecting apparatus using an active sensor such as an infrared sensor or ultrasonic sensor constantly emits light, or keeps oscillating. Therefore, it consumes a large amount of electric power. Also, this apparatus is cable of covering only a limited narrow area, since restrictions are imposed on the positional relation between the emitting portion, or oscillating portion, and the light-receiving portion. In order to compensate for the dead angle, the sensor must be divided into plural separate portions which are separated from the signal-processing portion.
The apparatus comprising the passive sensor having the shutter mechanism has a portion that is invariably operating. Therefore, it is difficult to power this apparatus by a battery, and it is impossible to fabricate it as a unit.